Thermostatic temperature control



R. AMSLER THBRIOSTATIC TEMPERATURE CONTROLLING MEANS Filed June 19. 1936 Sept. 12, 1939.

//v vE/v role A TTORNEYS Patented Sept. 12, 1939 UNITED STATES THERMOSTATIC TEMPERATURE CONTROL- LING MEANS Robert Amsler, Cham, Switzerland, assignor to Landis & Gyr, A.G., a corporation of Switzerland Application June 19, 1936, Serial No. 86,062

' In-Switzerland June 24, 1935 3 Claims.

The invention relates to new and useful improvements in thermostatic controlling devices and more especially to such improvements especially adapted to control electrical circuits carry- 5 ing relatively large amountsof energy.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements', combinations and improvements herein shown and described.

The accompanying drawing, referred to herein and constituting a part hereof, illustrates one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Of the. drawing:

Fig. 1 is a side elevation of a mechanism embodying the invention but omitting any circuit controlling devices;

Fig. 2 is a view similar to Fig. 1 and showing also a reversing switch operated by the thermostatic device;

Fig. 3 is a plan view. corresponding to Fig. 2;

Fig-4 is an elevation showing the thermostat controlling a circuit opening and closing device;

and

Fig. 5 is a sectional fragmentary detail.

Objects of the invention are to provide a thermostatic control, for use as a room temperature regulator or otherwise, which is simple, strong,

inexpensive and reliable, and which possesses high sensitivity; and has the capability of controlling large currents; to provide in such a mechanism a bi-metallic element which has relatively a great.

area of exposure to the atmosphere as compared to its mass, and has resultantly relatively small thermal inertia and also great stiffness of the bi-metallic strip on a free limb thereof, thereby rendering available a relatively large force or power to operate the switch.

As preferably embodied, the invention is applied to that type of mechanism wherein a permanent magnet is employed to furnish at least a portion of the energy for actuating the switch, or other circuit or temperature controlling device;

that is, a magnetically attractedmember is carried by the bi-metallic strip and is maintained at one pole of the magnet, and the temperature induced movement of the strip begins to move the member across the gap and from a median point in the movement the other pole of the magnet (Cl. 20o-139) imparts a quick and relative powerful movement to the magnetically attracted member, and effects most or all ofthe circuit changing movement, as the initial movement of the member across the gap may be idle so far as the switch actuation is 5 concerned. Referring now in detail to the embodiment of the invention illustrated by way 0f example in the accompanying drawing, the mechanism is mounted on the back or frame plate I, and is enclosed within a casing 2. within the casing is a permanent magnet 6 held in position on a bracket '1, mounted on the frame plate I, by means of a screw bolt 8. The thermostatic element consists of a bi-metallic strip or sheet I I which is of very great width as compared 15 to its thickness, as will be seen from comparison of Fig. 3 with the other figures. The sheet II as embodied is bent in a general U-shape or hook shape, and comprises a relatively short arm I2 which is fixed at its end to a support by suitable 2u means such as screws I3. The other arm I 4 of the bi-metallic sheet I I is much longer and terminates adjacent to the poles I5 and I6 of the permanent magnet 6. Fixed to the end of the free arm I4 of the bi-metallic sheet is a magnetically attracted 2 member 2I, such as an iron plate, and this magnetically attracted member is located between the poles I5 and I6 of the magnet 6.

The means for setting the mechanism for a desired temperature comprises devices for placing 30 the bi-metallic sheet I I under initial spring stress so as to resist to a predeterminable degree the movement of the sheet due to certain temperature changes. As embodied, the support for the end of the short arm I2 of the mi-metallic sheet I I com- 35 prises a cross bar 24, to which said arm is fastened by the screws I3. At either end thereof the bar I4 is formed into curved outwardly extending arms 25 and 26, which arms at their ends are mounted pivotally on a rod 21. The rod 21 is mounted in 0 4arms 28 and 29 integral with and extending outwardly from a plate 30, which is attached to the frame plate I by screws 3|. The shaft 21 is approximately in a plane passing between the poles of the magnet and perpendicular to its field. The 45 embodied means for variably positioning the support for the thermostatic element comprises a bar 35 having right angled arms 36 and 31 extending outwardly at either end thereof, and the arms are pivotally connected at their outer ends to median 50 points on the arms 25 and 26 byv suitable means,- such as pivot screws 4I and 42.

Screw-threaded means are provided, engaged with the bar 35, to impose the desired or predetermined spring pressure on the thermostatic 55 Mounted 10i member., As embodied, a rod 43 is screw-threaded into a stud 44 fixed to and projecting from the trame plate il. A lock nut dv holds the rod Q3 in adjusted position. Enclosing the rod (it is a hollow sleeve 68, the lower end ci which rests upon a nut t5, likewise screw-threaded on the rod t3. and constituting an adjustable support for the sleeve llt. Sleeve it has an enlarged, externally screw-threaded cylindrical portion dll, which has screw-threaded engagement with the cross bar 35. The member ill extends through an opening in the casing 2, and on the outside a knob or turning handle di is fixed to the outer end of member llt. The temperature-indicating means comprises a scale 53 on the casing 2, and an arrow or other indicator dit on the knob cooperating therewith. By turning the knob 52 the bar :it may be either raised or lowered so as to swing the support 2li for the loi-metallic strip around its axis 2l, thereby placing initial spring tension on the magnetically attracted member di located in the air gap of the magnet and thereby varying the degree of pressure exerted by the member 2| against the magnet pole. if desired, a suitable spring 5l may be used to prevent loose motion or back lash and a curved spring 51 is shown fastened at 58 to the frame plate with its free end bearing on the bar 24 and exerting pressure opposltely to the support or pull of the member 48.

rlhe circuit controlling means moved or governed bythe bl-metallic sheet may be of various forms. As shown in Figs. 2 and 3, a circuit or pole reversing device is provided, in which an insulated plate 6| is iixed to the free end of the arm I4 of the ibi-metallic sheet alongside the plate 2|; This insulated plate carries a conducting contact piece or pin 62; to which is attached one end of a circuit Wire 63, flxed at its other end to a circuit terminal 6.4, carried -on the bracket 65, which is supported on the frame plate I. The contact piece 62 is moved by the bi-metallic sheet between pole pieces 66 and 61, and by passing from contact with one into contact with the other reverses the circuit. In Fig. 4 a circuit opening and closing device is shown, and comprises two spring contact pieces and 12 impelled together in circuit` closing position by their springs -13 and 14, which are mounted on a support '15, carried by the frame plate Fixed to the spring arm 14 is'a plate 'l1 of insulating/,material which extends into the pathway of a contact piece '18,l which is fixed on and extends from the end of the free arm i4 of the loi-metallic sheet alongside the plate 2|. Through the temperature controlled movement oi the arm I4, the piece i8 moves plate ll', and the circuit is opened and closed at the contacts lll and U2, and the preliminary movement of piece lt across the gap may be idle, and it can engage plate lll only when the magnetic pull is exerted on it. The two forms of circuit controlling means are illustrative and as such are not a part of the invention, as the thermosatic control may be applied to other controlling means of lmown or suitable form, such as multiple reversing and maire and break switches as well as other forms may be employed.

The invention in its broader aspects is not limited to the specic mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and Without sacrificing its chief advantages.

What l claim is:

l. A thermostatic device comprising a generally KLJ-shaped bimetallic sheet, having a short arm and a long arm,- circuit making and breaking means cooperating with the free end of the long arm, variably positionable means for holding the short arm in a normally xed, but variably settable position, said bimetallic sheet being of great breadth, but very thin, for presenting a very large, heat-exchanging surface for contact with the surrounding air, such sheet having a low thermal inertia whereby it is very sensitive to temperature changes, the great breadth of the sheet also providing a strong efective force at the free end of the long arm for operating said circuit making and breaking means.

2. The combination as claimed in claim 1, said variably positionable means including a bar extending transversely across and secured to the short arm of the sheet at the end thereof, a pair of arms secured to the respective ends of said bar and extending toward the bight of the U- shaped sheet, means for pivotally supporting the ends of said arms. and manually settable means for variably positioning and holding said arms in any desired adjusted position.

3. The combination as claimed in claim 1, wherein the width of the bimetallic sheet is approximately one-third of its total length.

ROBERT AMSLER. 

